Refining of mineral oils



April 18, 1944. H. J. DEMPSEY REFINING OF MINERAL OIL Filed March 22, 1941 WMM NWA

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Patented Apr. 18, 1944 Henry J. Dempsey, Elizabeth, N. J., assilnor to Standard Oil Development Company, a corporation of Delaware rApplication March 22, 1941, Serial No. 384,693 3 clims. (ci. zoo-5,14)

The present invention is concerned with relining of mineral oils. The invention especially relates to the refining of petroleum oils for the removal of objectionable color bodies therefrom and for the segregation and recovery of naturally occurring naphthenic acids. In accordance with the present process feed oils, particularly petroleum oils, are contacted under dei? inite temperature conditions with a catalyst comprising chromic oxide.

It is known in the art to refine petroleum oils for the production of high quality products by various procedures. In these operations it `is known to remove objectionable color bodies from the oil, for example, by treating the same with various absorbents such as bauxite, zeolite, contacting clays and the like. Furthermore, in various refining operations in which it is desired to secure arearrangement of the molecular strucunderstood by reference to the drawing illustrating one embodiment of the same. For purposes of illustration it is assumed that the feed oil comprises a petroleum oil boiling in the lubrieating oil boiling range. The feed oil is lntroduced into feed oil storage zone. 2 by means of line I, from where it is withdrawn by means of line 3 and passed to oil contacting zone d. In contacting zone 4l the oil is treated with fresh chromic oxide which is withdrawn from zone b and introduced by means of line 6 with chromic oxide which is withdrawn from zone 'l intocontacting zone t by means of line Temperature and pressure conditions are adjusted in zone d to secure the desired decolorization of the feed oil and to secure the desired removal of naphthenic acid constituents from the same. Adequate mixing of the chromic oxide and oil is secured in zone l by utilizing agitating means d.

The chromic oxide contacted oil is withdrawn from treating zone d by means of line l@ and passed into separating means il, which may comprise any suitable means adapted to secure separation between the treated oil and thei line i2 'and passed to chromic oxide contacted` oil) storage zone I4 by means of line il. From this zone the treated product is withdrawn by means of line l5 and further handled or reilned oily constituents from the chromic oxide and which will have substantially no e'ect on the color bodies and naphthenic acid constituents retained by the chromic oxide. For purposes of description,` the solvent is taken to be a "light petroleum naphtha which is withdrawn from storage zone I6 and introduced into filtering zone Il by means of line Il. The solution of naphtha and oily constituents removed in this washing operation is passed to naphtha recovery zone Il ,by means of line i9 wherein temperature and pressure conditions are adjusted to remove the light naphtha overhead by means of line 2li. The naphtha is returned to naphtha storage i6 and recycled to the system. The higher boiling oil constituents removed from the chromic oxide by means of the naphtha is withdrawn from naphtha recovery zone I8 by means of line 2l and preferably recycled with the fresh feed oil by passing the same to feed oil storage 2. However, in certain operations this oil may be withdrawn from the system by means of line 22 and handled as desired or combined with the treated oli product removed by means of line i5.

Spent chromic oxide containing adhered thereon color bodies and naphthenic acid constituents is withdrawn from separation zone It by means of line 23 and passed to a solvent refluxing zone 2d. In solvent refluxing zone 26 the spent chromic oxide is treated with a solvent .under conditions adapted to dissolve in the solvent the naphthenic acids to the exclusion of the color bodies. For the purpose of description it is assumed that the solvent comprises methyl alcohol which is withdrawn from alcohol storage 25 and introduced into solvent refiuxing zone 2t by means of line 26. In zone 2t the chromic oxide is refiuxed preferably at .the boiling point of the alcohol for a time period sumcient to dis solve in the alcohol the naphthenic acids. After a' sufiicient time period the mixture is withdrawn from zone 215 by means of line 2l, and passed through separating means 28 wherein the chromic oxide is separated from the alcoholic solu tion of naphthenic acids.

The chromic oxide is withdrawn from separating means 28 by means of line 29 and passed to a rotary kiln or equivalent means 30 wherein,

mic oxide is withdrawn from rotary kiln 80 by means oi' line Si and recycled to storage zone 1. The alcoholic solution comprising naphthenic acids is withdrawn from separating means 2l by means of line 32 and passed to alcohol recovery zone 33 wherein the alcohol is separated from the crude naphthenic acids, removed over-` head by means of line 3d, and recycled to storage zone 2b. The crude naphthenic acids are withdrawn from recovery zoned@ by means of line 53d, passed to crude'naphthenic acid storage 8S and withdrawn from the system by means of line di. These acids withdrawn from the system by means of line 3l may be further rened'for the production of refined naphthenic acids or for the segregation of particular naphthenic acids by methods known in the art, such as by esterication operations or by utilizing operations involving the formation oi salts.

It is to be understood that the present process may be widely varied. The operation may comprise a percolation operation. a batch stage treating operation, or a slurry of the chromic oxide may be employed. My invention essentially com- -prises contacting a feed oil with a chromic oxide catalyst at a temperature in the range below about 200 F. preferably at a temperature in the range from about 100 F. to 150 F. The operation generally is carried out under pressure conditions adapted to maintain the oil being treated in the liquid phase. In general, atmospheric pressure has been found to be entirely satisfactory.

The chromic oxide utilized may be of any particle size. As pointed out before, a' slurry of the chromic oxide may be employed or a powdered chromic oxide catalyst utilized. ,Under certain conditions it is desirable to employ the chromic oxide in conjunction with otherabsorbents. The amount of chromic oxide used may vary considerably and will depend upon the character of the feed oil. In general, it is preferred to employ from about 2 pounds to 10 pounds of chromic oxideper gallon of oil, preferably from about 4 pounds to 8 pounds, and to regulate the contact time from about two to ten minutes. In general, it is desirable to have the contact time below about five minutes.

My process may be adapted for the removal of color bodies from any feed oil containing the same and for the removal and recovery of nephthenic acid constituents. It is particularly ap plicable in the treatment of petroleum oils boiling in the heating oil and lubricating `oil boiling ranges. The spent chromic oxide may be regenerated by burning or by utilizing any suitable means, such as by washing with various solvents, as for example, liquefied normally gaseous hydrocarbons, lightnaphthas, or oxygenated substances such as various alcohols, ketones, and the like. The washing operation may be combined with a burning operation. In accordance with a preferred adaptation of the invention in which it is des to segregate relatively pure naphthenic acid constituents, the chromic oxide is regenerated by solvent treating the same, which treatment is preferably followed by a burning operation.

. In this latter operation it is preferred that the spent chromic oxide be treated in an initial stage with a primary solvent as, for example, light naphthas, liquefied normally gaseous hydrocarbons, such as propane, butane, and the like. The solvents used in this stage are selected from the general class of solvents which are characterized by having a preferential selectivity tor the oil constituents as compared to the color bodies and naphthenic acid constituents. The amount of primary solvent used is adjusted substantially to free the chromic oxide oi' oily constituents and to eifect substantially no removal of the naphthenic acids and 4color bodies from the chromic oxide.

'I'he chromic oxide after separation from the primary solvent is then contacted with a secondary solvent having a preferential selectivity for the naphthenic acid constituents as compared to the color bodies. In general, oxygenated solventsrof the class of alcohols and ketones are preferred. Especially desirable solvents are the relatively low boiling alcohols such as methyl and ethyl alcohol. When employing a solvent oi this character it is preferred to reflux the chromic oxide with the solvent for a sufilcient time period. In general, this time period is in the range from about 15 to 45 minutes. The amount of secondary solvent employed will vary widely` depending upon the general operating conditions. However, I have found that it is desirable to employ from about 0.5 to 4.0 volurnes of secondary solvent per volume of chromic oxide. Under these conditions, an appreciable quantity of the color bodies are retained on the chromic oxide and are subsequently removed therefrom by burning.

In order to illustrate the invention further, the following examples rare given which should not be construed' as limiting the same in any way whatsoever. y

Example 1 A Pennsylvania oil having a Saybolt viscosity inthe range from about to 200 was contacted with chromic oxide under the following conditions with the following results:

Adsorbent Cn0\..- CrgOl... Fullers earth lines. Adsorbents,lbs./gal. l.67..... 1.67..... 1.67. Adsorbent ago Fresh... Fresh... Fresh. Oontacttvmp....F. 360 160 300. Contact time minutos.. ii 5 5. Tag Robinson color oicontaetedoii.. 5 8% 9.

Example 2 A. feed 'oii derived from a Colombian crude oil and boiling in the lubricating oil boiling range was contacted with about three pounds of chromic oxide per gallon of oil at a temperature of about F. and at a contact time of about flve minutes, with results as follows:

Oil before Oil after contacting contacting Gravity, .-A. P. I-- 31.0 31.2 Open cu flash (A. S. T. M.). 295 295 Saybolt niversal viscosity 57 56 Pour point -..F.. -40 -40 Color, Tag Robinson.-. 3. 5 7.0 Neutralization number (A. B. T. M.).. 2. 92 2.0i N aphthenic acid content per cent.. l. 8 l. 2

` From the above, it is apparent that an appreciable removal oi' color bodies was secured from the oil. and that naphthenic acid constituents were likewise removed.

In the above operation based upon 1000 vo1.

umes of oil contacted, the results were as follows:

Neutrallza- Naphthenlo Volume tion acid by number volume Per cent Oil to contacting unita l, 000 292 1. 8 Oil from contacting unitsm-. 040 201 l. 2

' oily layer recovered as follows:

Neutraliza- Naphthenio Volume tion acid by number volume Per cent Oil recovered... 55 2. 3 l. 4

The chromic oxide was dried, washed with 95% methyl alcohol, and again refluxed. An oily lay'er was secured as follows: A

Neutraliza- Naphthenlc Volume tion acid by number volume l Per cent Layer recovered..- 2.0 107 l 61 The catalyst was then washed with beuzol, dried, and the combustible matter determined. The combustible matter was 0.26%.

From the above, it is apparent that by operating as described it is possible to segregate a crude naphthenic acid fraction whichmay be readily processed into refined naphthenic acids.

What I claim as new and wish to protect by Letters Patent is:

l. Process for the ,removal and recovery of naphthenic vacid constituents from a mineral oil containing the same, which comprises contacting said mineral oil at a temperature in the range from about F. to about 200 F. in the liquid state with a catalyst comprising as the essential active ingredient chromic oxide, segregating said chromic. oxide, and contacting the same with a primary solvent having the ability to remove therefromolly constituents and color bodies. separating the treated chrom'ic oxide and contacting the same with a secondary oxygenated solvent selected fromthe class consisting of ketones and alcohols whereby the naphthenic acid constituents are removed, removing the secondary solvent containing the naphthenic acid constitu ents and recovering the naphthenic acid constituents therefrom.

2. Process as dei-ined by claim 1 in which said primary solvent comprises a low boiling petroleum hydrocarbon and in which said secondary solvent comprises a ketone.

3. Process as deined by claim 1, in which said primary solvent comprises a liquefied normally gaseous hydrocarbon, and in which said secondary solvent comprises an alcohol.

i HENRY J. DEMPSEY. 

